I am sorry to hear about your son. But, the good news is great advances have been made in the treatment of heart failure.
I, too, have CHF.
I was diagnosed in 2020 with Dilated Cardiomyopathy with LBBB resulting in and stage CHF, as a result of a viral infection.
The first line of treatment is pretty much always a pharmaceutical one mostly because it is the least invasive one. And, for many people, it works quite well.
It worked for me for about 2 years. Then my EF dropped to 19% and it was decided that I needed to have a CRT implanted. (Mine has a defibrillator, as well, because I am at risk of sudden cardiac arrest but some are strictly pacemakers.) It is a type of pacemaker but much more advanced. That was 2 years ago and my quality of life so much better than before. The CRT - Cardiac Resynchronization Device or biventricular pacemaker - has been a revolutionary step forward in the treatment of heart failure. They are, as of yet, not all that common - only about 10% of all cardiac electronic devices are CRTs - but the numbers are growing.
As for limitations with a CRT, I know marathon runners who have CRTs, competitive bicyclists and people who do cross training. As for life expectations, I would be very surprised if he didn't get to live a very long and full life. This is a very active field of research and advances are being made all the time.
Hang in there, mom, and learn all you can about treatments for CHF, including CRTs. They are amazing technology.
All the best to you and your son.